Question

Find ????⋅ ???? if |????|=3 , |????|=9 , and the angle between ???? and ???? is π2 radians.

a.b = _______

Answer 1

`a{\cdot}b=0`

Explanation:

It is given that,

Magnitude of a A,
`|A|=3`

magnitude of B,
`|B|=9`

The angle betwern a and b is
`(\pi)/(2)\ rad=90^(\circ)`

Dot product,

`a{\cdot} b=|a||b|\ \cos\theta\\\\a{\cdot} b=3* 9* \ \cos(90)\\\\a{\cdot} b=0`

So, a.b is equal to 0.